Reactor and agitator useful in a process for making 1-chloro-3,3,3-trifluoropropene

ABSTRACT

Disclosed is a reactor and agitator useful in a high pressure process for making 1-chloro-3,3,3-trifluoropropene (1233zd) from the reaction of 1,1,1,3,3-pentachloropropane (240fa) and HF, wherein the agitator includes one or more of the following design improvements:
     (a) double mechanical seals with an inert barrier fluid or a single seal;   (b) ceramics on the rotating faces of the seal;   (c) ceramics on the static faces of seal;   (d) wetted o-rings constructed of spring-energized Teflon and PTFE wedge or dynamic o-ring designs; and   (e) wetted metal surfaces of the agitator constructed of a corrosion resistant alloy.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims domestic priority under 35 U.S.C. 119(e) tocommonly owned U.S. Provisional Application Ser. No. 61/697,373, filed 6Sep. 2012, the disclosure of which is hereby incorporated herein byreference.

BACKGROUND OF THE INVENTION

This invention is directed to an improved design for a reactor andagitator useful in a process for making 1-chloro-3,3,3-trifluoropropene(1233zd) from the reaction of 1,1,1,3,3-pentachloropropane (240fa) andHF. The compound 1233zd is a low global warming compound that hasapplications as a replacement for high global warming materials, forexample in foam blowing and aerosol propellant applications.

The designation 1233 is used herein to refer to all trifluoro,monochloro propenes, namely olefin compounds having the general formulaC₃H₂ClF₃. The designation 1233zd is used herein generically to refer to1,1,1-trifluo-3-chloro-propene, independent of whether it is the cisform or the trans form. The terms “cis-1233zd” and “trans-1233zd” areused herein to describe the cis- and trans-forms of1,1,1-trifluo-3-chlororopropene, respectively. The designation “1233zd”therefore includes within its scope cis-1233zd, trans-1233zd, and allcombinations and mixtures of these.

U.S. Pat. No. 6,844,475 teaches a process for producing 1233zd from240fa at low pressure and at temperatures lower than 150° C. Thedisclosure of this patent is hereby incorporated herein by reference.

U.S. Pat. No. 6,362,383 teaches a process for preparing1,1,1,3,3-pentafluoropropane (245fa) by (1) a first reaction step inwhich 1,1,1,3,3-pentachloropropane (240fa) is reacted with hydrogenfluoride in the liquid phase in the presence of a firsthydrofluorination catalyst under conditions that are suitable forobtaining a mixture of reaction products comprising1-chloro-3,3,3-trifluoropropene (1233zd) in substantial amount, and (2)a second reaction step in which the 1-chloro-3,3,3-trifluoropropene(1233zd) obtained from the first step is reacted with hydrogen fluoridein the liquid phase in the presence of a second hydrofluorinationcatalyst, and preferably while hydrogen chloride is continuously fed in,in order to obtain 1,1,1,3,3-pentafluoropropane (245fa). The disclosureof this patent is hereby incorporated herein by reference.

U.S. Patent Publication No. 2012-0296127 discloses a high pressureprocess to produce 1233zd, operating at moderate temperatures. Thedisclosure of this patent application is hereby incorporated herein byreference. In this process, hydrogen fluoride (HF) is used as a rawmaterial and HCl is produced as a co-product. Agitation is required forthe process. Because of the corrosive nature of the chemicals used andgenerated in the reaction, designing an agitator that will have anappropriate life is a challenge.

The present invention provides a suitable reactor and in particular anagitator used therein for conducting this process, wherein the agitatoris constructed with materials that resist the effects of the corrosivechemicals of the reaction.

SUMMARY OF THE INVENTION

This invention is directed to improved designs for a liquid phasereactor and agitator useful in a high pressure process for making1-chloro-3,3,3-trifluoropropene (1233zd) from the reaction of1,1,1,3,3-pentachloropropane (240fa) and HF, in which HCl is produced asa co-product. Given that agitation is required for this process both thereactor vessel and the agitator must be made out of corrosion resistantmaterials in order to have a useful lifetime for conducting thisprocess.

Thus, one embodiment of the invention is directed to a reactor andagitator useful in a high pressure process for making1-chloro-3,3,3-trifluoropropene (1233zd) from the reaction of1,1,1,3,3-pentachloropropane (240fa) and HF, wherein the agitatorincludes one or more of the following improvements:

-   (a) double mechanical seals with an inert barrier fluid or a single    seal;-   (b) ceramics (parts or coatings) are employed on the rotating faces    of the seal;-   (c) ceramics (parts or coatings) may also be used on the static    faces of seal;-   (d) wetted o-rings constructed of spring-energized Teflon and PTFE    wedge or dynamic o-ring designs; and-   (e) wetted metal surfaces of the agitator constructed of an    appropriate corrosion resistant alloy.

The high pressure liquid phase reaction of 240 and HF, with or without acatalyst, yields a product stream comprising 1233zd, byproducts, HCl andunreacted HF. In certain embodiments the pressure range is from 150 psigto 600 psig. In certain embodiments, a more preferred pressure range isfrom 230 psig to 500 psig and a most preferred pressure range is from350 psig to 450 psig.

In certain embodiments, the catalyst choices are selected from knownLewis acid catalysts. The preferred catalysts are TiCl₄ or SbCl₅, withTiCl₄ being more preferred. In certain embodiments, the most preferredchoice is operation of the reactor without employing any catalyst.

The typical byproducts observed in the reaction stream are precursors to1233zd such as 241fa, 242fa, and 243fa. These can easily be separatedfrom the reaction stream using known techniques and recycled.

In one embodiment of the high pressure process for making 1233zd, thereactants 240fa and HF are fed to a continuously stirred or agitatedreactor, having the improved agitator design described herein, operatingat high pressure, and;

(a) the resulting product stream comprising 1233zd, HCl, HF, and otherbyproducts are distilled and the bottoms product, rich in HF, isrecycled to the reactor;

(b) the overhead product from the distillation column is fed to a seconddistillation column to remove the HCl;

(c) the HCl in the overhead stream is scrubbed with water and recoveredas an aqueous solution;

(d) the bottom stream from the second distillation column is then phaseseparated to recover HF;

(e) the HF rich top layer of the phase separation is recycled back tothe reactor; and

(f) the phase separation bottom layer components including the desired1233zd are scrubbed, dried and distilled to meet commercial productspecifications.

As described above, in a high pressure process for the production of1233zd, the operating conditions of the reactor are extremely aggressiveand the process employs reactant materials that are highly corrosiveunder these reaction conditions. It has been found that certain designcharacteristics are especially preferred for the agitator design herein,including:

-   (a) double mechanical seal with an inert barrier fluid such as    fluorolube or a single seal.-   (b) silicon carbide (parts or coatings) on the rotating faces of the    seal.-   (c) silicon carbide (parts or coatings) may also be used on the    static faces of seal.-   (d) wetted o-rings constructed of spring-energized Teflon (such as    the OMNISEAL brand made by St. Gobain) and PTFE wedge or dynamic    o-ring design-   (e) wetted metal surfaces of the agitator constructed of an    appropriate nickel alloy such as Alloy 20, the Hastelloy alloys or    the Inconel alloys.

It should be appreciated by those persons having ordinary skill in theart(s) to which the present invention relates that any of the featuresdescribed herein in respect of any particular aspect and/or embodimentof the present invention can be combined with one or more of any of theother features of any other aspects and/or embodiments of the presentinvention described herein, with modifications as appropriate to ensurecompatibility of the combinations. Such combinations are considered tobe part of the present invention contemplated by this disclosure.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention as claimed. Other embodimentswill be apparent to those skilled in the art from consideration of thespecification and practice of the invention disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a preferred agitator design of the present invention.

FIG. 2 illustrates a preferred continuous stirred tank reactor vesseldesign of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As described above, in the high pressure process for the production of1233zd, the operating conditions of the reactor are extremely aggressive(e.g., 140° C. and 400 psig) and the process employs reactant materialsthat are highly corrosive under these reaction conditions. The processrequires agitation to allow the reaction to proceed. As such, the designof the agitator is critical to ensure an appropriate operating lifetimein the harsh conditions. The present invention is directed to one suchreactor and agitator design.

Key Characteristics of Agitator Design:

-   -   (a) Double mechanical seal with an inert barrier fluid such as        fluorolube.    -   (b) Silicon Carbide ceramics (or the like) on the rotating faces        of the seal.    -   (c) Silicon Carbide ceramics (or the like) may also be used on        the static faces of seal.    -   (d) Perfluoroelastomer o-rings and PTFE wedge design    -   (e) Wetted metal surfaces of the agitator are constructed of an        appropriate nickel alloy such as Alloy 20, the Hastelloy alloys        or the Inconel alloys.

As shown in FIG. 1, an agitator according to the present inventionincludes a double mechanical seal consisting of a ceramic material,e.g., silicon carbide and equivalents, on the rotating faces, wettedparts that are constructed of an appropriate nickel alloy, andspring-energized o-rings. The agitator may be installed in a top orbottom mount position.

As shown in FIG. 2, a reactor vessel according to the present inventionincludes an agitator of the style of FIG. 1, materials of constructionof an appropriate nickel, alloy (either solid or clad), and may containan external or internal heating or cooling system. The design may bemodified to feed reactants in the liquid or vapor phase and may be fedto the bottom or top of the vessel.

Corrosion resistant alloys are known and are preferred materials used inthe construction of the reactor vessel and agitator of the presentinvention. Some of the commercially available corrosion resistant alloysinclude the following:

(a) Nickel 200

Nickel 200 is commercially pure (99.6%) wrought nickel. It has goodmechanical properties and excellent resistance to many corrosiveenvironments.

(b) Monel® 400

Monel® nickel-copper alloy 400 is a solid solution alloy that may behardened only by cold working. It has high strength and toughness over awide temperature range and excellent resistance to many corrosiveenvironments.

(c) Inconel® 600

Inconel® nickel-chromium-iron alloy 600 is a standard engineeringmaterial for applications which require resistance to corrosion andheat. The alloy shows resistance to oxidizing conditions at hightemperatures or in corrosive solutions.

(d) Inconel® 625

Inconel® nickel chromium alloy 625 is used for its high strength,excellent fabricability (including joining), and outstanding corrosionresistance.

(e) INCO C-276

INCO alloy C-276 is known for its outstanding corrosion resistance in awide range of severe media. The high nickel and molybdenum contentsprovide good corrosion resistance in reducing environments whilechromium imparts resistance to oxidizing media.

(f) Incoloy® Alloy 800

Incoloy® alloy 800 is a widely used material of construction forequipment that must have high strength and resist oxidation,carburization, and other harmful effects of high-temperature exposure.The chromium in the alloy imparts resistance to oxidation and corrosion.

(g) Incoloy® 825

Incoloy® alloy 825 is a nickel-iron-chromium alloy with additions ofmolybdenum, copper and titanium. The alloy's chemical composition isdesigned to provide exceptional resistance to many corrosiveenvironments.

(h) Alloy 020

INCO alloy 020 is an austenitic nickel-iron-chromium alloy withadditions of copper and molybdenum. The nickel content makes INCO alloy020 resistant to chloride-ion stress-corrosion cracking Copper andmolybdenum give resistance to reducing environments. The molybdenumcontent also provides good resistance to pitting and crevice corrosion.The chromium gives resistance to oxidizing environments.

(i) Hastelloy®

Hastelloy® is the trademark name for a range of twenty two differenthighly corrosion-resistant metal alloys loosely grouped by themetallurgical industry under the material term “superalloys” or“high-performance alloys”. The predominant alloying ingredient istypically the transition metal nickel.

Working Example

An agitator is constructed of Alloy 20 wetted parts and a doublemechanical seal with fluorolube barrier fluid, silicon carbide on allseal faces, spring-energized Teflon o-rings and a PTFE wedge system wasoperated at conditions ranging from 100 to 400 psig and 90° to 145° C.in a process to produce HFCO-1233zd from HF and HCC-240. The agitatoroperated successfully for several months.

Comparative Example 1

An agitator constructed of Alloy 020 wetted parts and a doublemechanical seal with fluorolube barrier fluid, silicon carbide on allseal faces, perfluoroelastomer o-rings and a PTFE wedge system wasoperated at conditions ranging from 100 to 400 psig and 90° to 145° C.in a process to produce HFCO-1233zd from HF and HCC-240. The agitatorseal system failed after 3 weeks of operation due to chemical attack ofthe perfluoroestomer wetted o-rings.

Comparative Example 2

An agitator constructed of Alloy 020 wetted parts and a doublemechanical seal with fluorolube barrier fluid, tungsten carbide on therotating seal face, perfluoroelastomer o-rings and a PTFE wedge systemwas operated at conditions ranging from 100 to 150 psig and 90° to 100°C. in a process to produce HFCO-1233zd from HF and HCC-240. The agitatorseal system failed after 2 weeks of operation due to failure of the sealfaces.

As used herein, the singular forms “a”, “an” and “the” include pluralunless the context clearly dictates otherwise. Moreover, when an amount,concentration, or other value or parameter is given as either a range,preferred range, or a list of upper preferable values and lowerpreferable values, this is to be understood as specifically disclosingall ranges formed from any pair of any upper range limit or preferredvalue and any lower range limit or preferred value, regardless ofwhether ranges are separately disclosed. Where a range of numericalvalues is recited herein, unless otherwise stated, the range is intendedto include the endpoints thereof, and all integers and fractions withinthe range. It is not intended that the scope of the invention be limitedto the specific values recited when defining a range.

It should be understood that the foregoing description is onlyillustrative of the present invention. Various alternatives andmodifications can be devised by those skilled in the art withoutdeparting from the invention. Accordingly, the present invention isintended to embrace all such alternatives, modifications and variancesthat fall within the scope of the appended claims.

What is claimed is:
 1. A process for the manufacture of 1233zdcomprising the steps of: (a) reacting 240fa and HF without a catalyst inan agitator stirred reactor, wherein the agitator comprises wetted metalsurfaces and two spaced-apart sets of agitator blades mounted on anagitator shaft, wherein the wetted metal surfaces of the agitatorcomprise a corrosion resistant alloy selected from the group consistingof Alloy 020, the Hastelloy alloys and the Inconel alloys, and thereactor is operated at a pressure range of 350 psig to 450 psig and at atemperature range of from 90° C. to 145° C. to produce a product streamcomprising 1233zd, HCl, HF, and other byproducts; (b) distilling theproduct stream from step (a) into a first overhead product and a firstbottoms product rich in HF; (c) distilling the first overhead productfrom step (b) to form a second overhead product containing HCl and asecond bottoms product containing organic components and HF; (d) phaseseparating the second bottoms product from step (c) to separate the HFfrom the organic components; and (e) scrubbing, drying, and distillingthe organic components from step (d) to provide purified 1233zd.
 2. Theprocess of claim 1, wherein the HF from step (b) is recycled to thereactor.
 3. The process of claim 1, wherein the HCl from step (c) isscrubbed with water and optionally recovered as an aqueous solution. 4.The process of claim 1, wherein the HF from the phase separation in step(d) is recycled back to the reactor.
 5. A process for the manufacture of1233zd comprising the steps of: (a) reacting 240fa and HF with acatalyst in an agitator stirred reactor, wherein the agitator compriseswetted metal surfaces and two spaced-apart sets of agitator bladesmounted on an agitator shaft, wherein the wetted metal surfaces of theagitator comprise a corrosion resistant alloy selected from the groupconsisting of Alloy 020, the Hastelloy alloys and the Inconel alloys,and the reactor is operated at a pressure range of 350 psig to 450 psigand at a temperature range of from 90° C. to 145° C. to produce aproduct stream comprising 1233zd, HCl, HF, and other byproducts; (b)distilling the product stream from step (a) into a first overheadproduct and a first bottoms product rich in HF; (c) distilling the firstoverhead product from step (b) to form a second overhead productcontaining HCl and a second bottoms product containing organiccomponents and HF; (d) phase separating the second bottoms product fromstep (c) to separate the HF from the organic components; and (e)scrubbing, drying, and distilling the organic components from step (d)to provide purified 1233zd.
 6. The process of claim 5, wherein thecatalyst comprises one or more Lewis acid catalysts.
 7. The process ofclaim 6, wherein the Lewis Acid catalyst is selected from the groupconsisting of TiCl₄, SbCl₅, and mixtures thereof.
 8. The process ofclaim 7, wherein the catalyst is TiCl₄.